Objective To investigate the mechanism by which follicular fluid from endometriosis (EM) patients blocks mouse oocyte maturation and the effect of Neiyi Recipe-medicated serum on the effect of the follicular fluid. Methods A total of 20 follicular fluid samples from infertility patients due to EM (n=10) or fallopian tube factors (control group, n=10) were clinically obtained. Neiyi Recipe-medicated serum was obtained by treating mice with intragastric administration, and were divided into 4 medium groups: Group A (control), group B (control follicular fluid), group C (EM-follicular fluid) and group D (EM-follicular fluid + Neiyi Recipe-medicated serum). The mouse germinal vesicle (GV) oocytes were cultured in the above 4 types of media for in vitro maturation. And the maturity rates of oocytes in different groups were calculated and the concentrations of reactive oxygen species in the cells were analyzed by fluorescence staining and laser scanning confocal microscope. Results The maturity rate of oocytes in group C (42.5%) was significantly lower than those in group A (81.7%), group B (56.3%) and group D (51.0%) (P<0.05). The average fluorescence intensity of group C (0.056 8±0.025 1) was significantly higher than those of group A (0.005 1±0.014 8, P<0.01) and group B (0.037 1±0.010 2, P<0.05), but with no significant difference found when compared with that of group D (0.050 4±0.007 0). Conclusion EM-follicular fluid can block the maturation of mouse oocytes, which may be due to the enhanced oxidative stress in oocytes caused by EM-follicular fluid. Neiyi Recipe-medicated serum can improve the blocking effect of EM-follicular fluid on mouse oocyte development.